JP2012218115A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad having a polishing layer made of fabric capable of improving flatness of a wafer and stabilizing a polishing rate, in which supply of slurry and discharge of waste liquid are controlled in a well-balanced manner.SOLUTION: The polishing pad is formed with the polishing layer 1 and a support layer 3 laminated together. In the polishing pad, the polishing layer 1 is made of the fabric 6 with mesh opening of 50 to 200 μm and thickness of 100 μm or below, and a groove 5 is formed in the support layer 3. The groove 5 communicates to a polishing surface.

Description

  The present invention relates to a polishing pad.

  In recent years, with high integration and high density of semiconductor devices, a technique for flattening the wafer surface with high accuracy is required. One such wafer planarization technique is a chemical mechanical polishing (CMP) method. In this method, the wafer is pressed against a rotating polishing pad and the wafer surface is polished with the polishing pad while supplying a chemical polishing liquid (slurry).

  When polishing a polishing object such as a silicon wafer, a polishing pad such as a polyurethane-impregnated nonwoven fabric pad “SUBA” (registered trademark) or a polyurethane foamed resin pad “MH” (registered trademark) is generally used. For the purpose of promoting the supply of polishing liquid and the discharge of waste liquid after polishing, polishing pads having grooves and holes on the polishing surface have been studied.

  Patent Document 1 describes a polishing pad in which a large number of waste liquid discharge holes opened on the surface of the polishing pad are provided, and a plurality of waste liquid discharge paths are provided in a lower layer member communicating with each of the waste liquid discharge holes. Therefore, it is described that the polishing rate is stabilized by preventing mixing of the slurry and the waste liquid.

  Patent Document 2 describes a polishing pad having a first groove below the second groove and communicating with the first groove. And also in patent document 2, like patent document 1, since the dust which fell into the 1st groove | channel does not flow back into the 2nd groove | channel, it can prevent mixing of a slurry and waste liquid, and can reduce the foreign material adhering to a wafer. It states that it can be done.

  Further, Patent Document 3 discloses a polishing pad in which through holes and radiation grooves are formed in a base layer and circular grooves are formed in a polishing layer. With such a structure, the slurry is uniformly supplied to the entire polishing surface through the intersection of the radial groove and the circular groove, so that the polishing quality can be satisfactorily finished without causing a reduction in the polishing rate. It states that it will be possible.

  On the other hand, polishing cloth made of woven fabric has been studied (Patent Document 4).

JP 2001-150333 A JP 2009-297817 A JP 2011-000676 A JP 2007-308821 A

  The inventors have also applied the polishing liquid (slurry) to the entire polishing pad and after polishing in order to improve the flatness of the wafer and stabilize the polishing rate even in a polishing cloth made of a woven fabric as in Patent Document 4. We thought that it was important to control prompt discharge of waste liquid in a well-balanced manner. And it tried to form a groove | channel and a hole in the grinding | polishing layer which consists of textiles.

  However, it is very difficult to form grooves and holes on the polishing surface, which has been studied for polishing pads such as polyurethane-impregnated nonwoven fabric pads and polyurethane foam resin pads, as described above, in the case of a polishing layer made of woven fabric. there were. This is because if the grooves and holes are formed on the polished surface by cutting, the fibers constituting the fabric are cut.

  Therefore, the present inventors have conceived that a polishing layer made of a woven fabric and a support layer are laminated, grooves are formed in the support layer, and openings are formed in the woven fabric that is the polishing layer. In this way, it was thought that the supply of the slurry to the entire polishing pad and the quick discharge of the waste liquid after polishing could be performed in a well-balanced manner.

  Here, Patent Documents 1 to 3 show a polishing pad having a groove in the underlayer, but at the same time, a groove is formed in the polishing layer, and the groove in the underlayer is a waste liquid after polishing. It is only responsible for either the rapid discharge of the slurry or the supply of the slurry to the entire polishing pad, and cannot be applied as it is.

  An object of the present invention is to provide a polishing pad having a polishing layer made of a woven fabric in which the supply of slurry and the discharge of waste liquid are controlled in a well-balanced manner and the flatness of the wafer is improved and the polishing rate is stabilized. .

  Here, the present inventors considered that in Patent Document 1, the hole diameter of the discharge hole is as large as 1 to 5 mm, so that only the discharge of the waste liquid is performed. Further, in Patent Document 2, an example in which the groove width is 2 mm is shown, and the intersection of the grooves is also large, so that it was thought that only the discharge of the waste liquid was performed. Furthermore, in Patent Document 3, it was considered that the intersection between the radial groove and the circular groove was as large as 1 mm square, and therefore only the slurry was supplied.

  Also, attention was paid to the thickness of the polishing layer. In Patent Document 1, the thickness of the polishing layer is considered to be about the hole diameter from the figure, and an example of about 1 to 5 mm is shown. In Patent Document 2, it is regarded as a groove width from the figure, and an example of about 2 mm is shown. In Patent Document 3, an example of a groove depth of about 2.5 mm is shown from the drawing. It was considered that when the polishing layer was thick, only the drainage of the waste liquid or the supply of the slurry was performed.

  As a result of intensive studies, the present inventors have found that the mesh opening is 50 to 200 μm and the thickness is 100 μm or less in order to supply the slurry and discharge the waste liquid in a well-balanced manner.

  That is, the present invention is a polishing pad formed by laminating a polishing layer and a support layer, the polishing layer is made of a woven fabric having an opening of 50 to 200 μm and a thickness of 100 μm or less, and grooves are formed in the support layer. The polishing pad is characterized in that the groove communicates with the polishing surface.

  According to the polishing pad of the present invention, it is possible to have a wafer with excellent flatness and a stable polishing rate over time.

It is sectional drawing which shows typically the polishing pad to which this invention is applied. It is a top view which shows typically an example of the support layer which has the grid | lattice-like groove | channel of embodiment. It is a top view which shows typically an example of the support layer which has the radial groove | channel of embodiment. It is a photograph substitute figure which shows the polishing surface of the polishing pad of embodiment.

  Hereinafter, the polishing pad of the present invention will be described in more detail.

  As shown in FIG. 1, the polishing pad of the present invention is a polishing pad formed by laminating a polishing layer and a support layer, and the polishing layer is made of a woven fabric having an opening of 50 to 200 μm and a thickness of 100 μm or less. A groove is formed in the layer, and the groove communicates with the polishing surface. This is designed based on the following technical idea.

  When a polishing object such as a silicon wafer or glass is polished flatly, polishing is performed by relatively rotating the polishing pad and the wafer while supplying slurry onto the polishing pad. At this time, the slurry is uniformly supplied onto the polishing pad, and at the same time, the waste liquid containing polishing debris is quickly discharged, whereby wafer flatness is excellent and polishing with a polishing rate stabilized over time becomes possible. In order to satisfy these conditions using a polishing pad made of a woven fabric of the polishing layer, a groove was formed in the surface layer of the support layer, and the woven fabric as the polishing layer had an opening.

  Next, the support layer in this invention is demonstrated.

  The support layer in the present invention has not only a role for holding the polishing layer and a role as a cushion generated during polishing, but also a role as a flow path for slurry and waste liquid, thereby supplying slurry and waste liquid. The discharge can be made well balanced, which can contribute to the improvement of the flatness within the wafer surface and the stabilization of the polishing rate over time. Therefore, it is necessary that a groove is formed in the support layer.

  If it is only necessary to control the balance between the supply of slurry and the discharge of waste liquid, it is conceivable to create grooves on the polishing surface instead of the support layer, but the polishing layer of the present invention comprises a woven fabric, When grooves or holes are formed on the surface by cutting, the fibers constituting the fabric are cut, and the durability is significantly reduced. In that respect, by forming a groove in the support layer, it becomes possible to prevent the fiber from being cut and to improve the durability.

  In order to promote the supply of polishing slurry and the discharge of waste liquid, the groove is preferably extended to the pad end, the shape of the groove is not particularly limited, but concentric, spiral, Examples include a lattice shape and a radial shape, and a lattice shape or a radial shape is preferable. It is also preferable to use a combination of grooves including at least one groove extending to the pad end, such as concentric circles and radials, or spirals and radials.

  When forming lattice-like grooves in the support layer, if the pitch between the grooves is narrow, the shearing force generated between the wafer and the polishing pad during polishing may cause the pad to be easily deformed and edge fringing may occur. . If the pitch of the grooves is too wide, it may be difficult to obtain the effect of supplying slurry and discharging waste liquid. Therefore, the groove pitch is preferably 5 to 30 mm, and more preferably 10 to 20 mm. Further, in order to make the supply of slurry and the discharge of waste liquid uniform over the entire polishing surface, it is preferable that the groove pitches in the X direction and Y direction are the same (FIG. 2).

  Moreover, when forming a radial groove | channel, it is preferable that the number of radial grooves is in the range of 4-32 from the same viewpoint as the above, and it is more preferable that it is 16-32 (FIG. 3).

  If the groove has a concentric or spiral shape, the waste liquid discharge is delayed and the polishing debris aggregates, which may easily cause scratches on the wafer. Furthermore, in order to prevent new slurry from entering the groove, the concentration of abrasive grains contained in the slurry may be biased on the polishing surface, which may reduce the flatness of the wafer.

  Groove machining on the surface of the support layer can form predetermined grooves by cutting or embossing. For the cutting process, a known precision machining technique such as a method using a precision cutting machine or a method of machining by laser or fluid injection can be employed.

When the volume of the groove is large, the supply of slurry and the discharge of the waste liquid are further promoted, but the pad may be deformed by the shearing force generated at the time of polishing, and the edge drooping amount of the wafer may be increased. On the other hand, if the volume of the groove is too small, the supply of polishing slurry and the discharge of waste liquid are delayed, which may cause a decrease in wafer flatness and a decrease in polishing rate over time. From these viewpoints, the cross-sectional area of the grooves in the polishing pad of the present invention is preferably from 0.1 to 2 mm ^2, and more preferably 0.2 to 1.5 mm ^2.

  If the thickness of the support layer is too thin, it may be difficult to form a groove, and it may be difficult to absorb the vibration of the polishing surface plate, thereby reducing the wafer flatness. On the other hand, if the support layer is too thick, the manufacturing cost of the polishing pad may increase. Therefore, the thickness of the support layer is preferably 0.5 to 10 mm, more preferably 0.5 to 5 mm, and further preferably 0.5 to 2 mm.

  The support layer used in the present invention is in the form of a flat sheet, and is not particularly limited as long as it has a thickness for performing grooving, but a resin sheet, foamed foam, nonwoven fabric, or the like can be used.

  Among the resin sheets, those having rubber elasticity are preferably used because it is easy to obtain an appropriate hardness and chemical resistance and relatively easy to control the hardness and flatness of the rubber sheet surface. Moreover, it is preferable that it is a rubber sheet also from a viewpoint of absorbing the vibration from a surface plate and improving polishing precision. The rubber sheet material is natural rubber (NR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene rubber (EPT), isobutylene isoprene rubber (IIR), chlorosulfonated polyethylene rubber (CSM), styrene. Examples include butadiene rubber (SBR), butadiene rubber (BR), silicone rubber (SR), fluorine rubber (FR), and urethane rubber (UR), but considering mechanical strength, rebound resilience, chemical resistance, and the like. Of these, acrylonitrile butadiene rubber and urethane rubber are preferable. Among these, urethane rubber is preferably used in view of versatility and flatness of the rubber sheet.

  When the polishing pad of the present invention is applied for rough polishing of a semiconductor bare wafer such as silicon or glass (optical glass, glass for flat panel display, glass mask used for exposure, etc.), the Asker A hardness of the support layer is 70. The above is preferable. As a result, it is possible to suppress not only the entire polishing pad but also the deflection corresponding to the site flatness (about 10 to several tens of mm), and preferentially polish the convex portion among the irregularities on the wafer surface. It is possible to improve the flatness of the wafer. For this reason, it is preferable that the support layer has a higher hardness. Specifically, the Asker A hardness is more preferably 80 or more, and further preferably 85 or more.

  On the other hand, when the polishing pad of the present invention is applied for bare wafer polishing such as single crystal silicon or glass finish polishing, the support layer preferably has an Asker A hardness of less than 70. As a result, the polishing pad deforms and follows along the warp and undulation of the entire wafer, so that the surface roughness of the wafer can be improved by removing minute irregularities of several nanometers to several micrometers on the wafer surface. . Therefore, the hardness of the support layer is preferably relatively small, the Asker A hardness is more preferably 65 or less, and further preferably 60 or less.

  When the thickness of the support layer is thin, the hardness can be evaluated by the micro rubber A hardness. In this case, the micro rubber A hardness is preferably less than 70, more preferably 65 or less, and even more preferably 60 or less.

  When used for CMP of a semiconductor oxide film or metal film, the support layer preferably has an Asker A hardness of 60 to 90. Thereby, the flatness of the wafer can be improved while following the unevenness of the wafer.

  Next, the polishing layer in the present invention will be described.

  In the polishing pad of the present invention, it is necessary that the woven fabric that becomes the polishing layer has a mesh size of 50 to 200 μm. The reason for using a fabric with openings in the polishing layer is that the slurry supplied to the polishing surface flows into the groove of the support layer and penetrates the entire pad, and then the slurry is supplied again from the groove to the polishing surface. It is for making it a structure. Further, when the size of the opening is within the above range, waste liquid containing polishing debris generated on the polishing surface is promptly flowed into the groove and efficiently discharged out of the system. The effect of reducing scratches can also be obtained. These effects are easier to obtain as the aperture is larger. On the other hand, when the mesh is small, the amount of slurry retained per unit area increases and the polishing rate can be improved. In consideration of the balance between the two, the size of the mesh opening is preferably 60 to 150 μm, and more preferably 60 to 100 μm.

  Here, the opening in the present invention means a pore formed by being surrounded by warp and weft of the fabric, and the pore penetrates in the thickness direction of the fabric. FIG. 4 is a photograph showing an example of the woven fabric used in the present invention, and the opening portion 7 is indicated by a square.

  In the present invention, the groove needs to communicate with the polishing surface. Here, the woven fabric constituting the polishing layer has an opening, and a part of the opening is arranged so as to contact the groove. Therefore, the groove communicates with the polishing surface, and the slurry in the groove is used as the polishing surface. It becomes possible to discharge waste liquid after supply or polishing into the groove.

  The size of the opening can be calculated from the square root of the opening area. In the present invention, the surface of the fabric affixed to the surface of the polishing pad was observed with a scanning electron microscope (SEM), 20 different locations were measured within the same fabric, and the average value was taken as the size of the opening.

  The polishing pad of the present invention is not particularly limited as long as the polishing layer has a mesh size of 50 to 200 μm and a thickness of 100 μm or less, and various multifilament twisted yarn fabrics and monofilament fabrics can be used. When such a woven fabric is used, the size of the openings can be regularly arranged on the entire polishing surface, whereby the flow of the polishing slurry acting on the wafer can be made uniform. In particular, since the fiber bundle of the multifilament twisted yarn fabric is twisted by bundling single fibers, the surface area is increased as compared with the monofilament fabric. Therefore, it is preferable because more abrasive grains can be held on the polishing surface, the polishing rate can be improved, and the amount of slurry to be used can be reduced.

  Here, when a multifilament woven fabric that is not twisted is used, the fiber may be opened by friction generated by polishing, and the size of the mesh may vary. For this reason, there are cases where the polishing slurry flow and the amount of slurry retained are different at any location on the pad, and the wafer cannot be uniformly polished. Further, since the waste liquid after polishing may not be appropriately discharged, polishing waste may adhere to and accumulate on the woven fabric, resulting in clogging, resulting in a decrease in the polishing rate, and generation of scratches on the wafer.

  Further, in a multifilament woven fabric that is not twisted, the single fiber may be worn or cut by friction generated by polishing, but the effect of improving durability can be obtained by twisting. For this reason, the twisted yarn is preferably strongly twisted.

  The term “strong twist” as used herein refers to those twisted 1,000 times or more per 1 m of yarn length (twist number of 1,000 T / m or more), and indicates the convergence and durability of each single fiber in the multifilament. In order to improve, the number of twists is preferably 1,500 T / m or more, more preferably 2,000 T / m or more. The number of twists can be determined by observing the surface layer of the woven fabric with an optical microscope, SEM, or the like, and measuring the number of warp or weft twisted wires constituting the woven fabric.

  The thickness of the fabric used for the polishing layer is required to be 100 μm or less. As a result, it becomes possible to supply the polishing slurry in the groove to the polishing surface, and at the same time, when the wafer and the polishing pad are pressed at the time of polishing, the shape and size deformation of the opening of the fabric that is the polishing layer is suppressed. As a result, it is possible to achieve the effects as designed. For this reason, the thickness of the woven fabric is preferably 80 μm or less, and more preferably 70 μm or less. When the thickness of the woven fabric exceeds 100 μm, the amount of the slurry that has penetrated into the groove is supplied again to the polishing surface is reduced, and the slurry becomes insufficient on the polishing surface, which is not preferable.

  The thickness of the fabric is indicated by the thickness of the portion 6 in FIG. 1, and can be specified by observing the cross section of the fabric with an SEM. Specifically, the distance between the warp surface of the fabric surface and the weft surface of the back surface of the fabric at the intersection of the warp and weft of the fabric is measured, and the average value at five different locations in the fabric is taken as the thickness.

  As the woven fabric used in the present invention, a woven fabric having a woven structure such as plain weave, twill weave, and satin weave can be used. It is preferable because it is excellent.

  An organic polymer is used as the material of the fibers constituting the fabric of the present invention. Examples of organic polymers include organic polymers that can be wet-spun, such as polyvinyl alcohol (PVA) and polyacrylonitrile (PAN). However, since wet spinning is rarely equipped with spinning equipment with a low discharge rate, filaments can be formed at a low discharge rate. From the viewpoint of easy production, a thermoplastic polymer that can be melt-spun is preferred. Examples of the thermoplastic polymer used herein include polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), nylon 6 (N6), and nylon 66 (N66). ), Nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 46 (N46), nylon 56 (N56) and other polyamides, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) ), And further, elastomers such as polyether ester and thermoplastic PU, liquid crystal polyester, polyphenylene sulfide (PPS), and the like.

  When the fiber is polyamide, the hydrophilicity of the polymer is high, and therefore, when used as a polishing pad, familiarity with an aqueous slurry is good and preferable. Further, when polishing a wafer, an alkaline slurry is usually used, but polyamide has an advantage of resistance to alkalinity, and has an advantage that a pad has a long life. Furthermore, since polyamide is supple and excellent in wear resistance, it is preferable from the viewpoint of extending the life of the pad. Among polyamides, N6, N66, and N12 are preferable in view of versatility.

  In addition, when the fiber is polyester, it is superior in strength retention and dimensional stability when wet compared to polyamide. Among polyesters, PET is preferable from the viewpoint of versatility, and PTT and PBT are preferable from the viewpoint of alkali resistance and wear resistance.

  In the case of polishing and CMP of a compound semiconductor wafer, the alkalinity and acidity of the slurry may be increased, and various additives such as an organic solvent, an oil component, and an oxidizing agent may be added. For this reason, polyolefin and PPS are preferable from the viewpoint of chemical resistance. PP is preferred from the viewpoint of versatility.

  Next, the interlayer adhesive layer in the present invention will be described.

  Here, the interlayer adhesive layer refers to a portion indicated by 2 in FIG. 1 and is provided for bonding the polishing layer and the support layer. Although the interlayer adhesion “layer” is used, the entire interface between the polishing layer and the support layer is not covered with the interlayer adhesion layer, and there is no interlayer adhesion layer in the groove formed in the support layer. Since the polishing layer has mesh openings, the groove and part of the polishing surface communicate with each other, allowing slurry in the groove to be supplied to the polishing surface and discharging waste liquid after polishing into the groove. Become.

  In the polishing pad of the present invention, the interlayer adhesive layer between the polishing layer and the support layer is not particularly limited, and various adhesion methods such as pressure-sensitive adhesive, chemically reactive adhesive, and fusion of thermoplastic resin can be used. is there. It is also possible to use a direct heat fusion method in which a support layer made of a thermoplastic elastomer is used, and the surface is heated and softened to bond the woven fabric.

  When using a pressure sensitive adhesive as an interlayer adhesive layer, it is preferable to use a pressure sensitive adhesive whose composition is a silicone adhesive. Here, an adhesive having an acrylic or rubber composition generally used as an adhesive tape is usually not excellent in water resistance and chemical resistance, and depending on the type and processing conditions of the polishing slurry, There is a problem that the pressure-sensitive adhesive deteriorates due to properties (for example, alkalinity, acidity, oxidation property, etc.) and peels off at the interface between the polishing layer and the interlayer pressure-sensitive adhesive layer or at the interface between the interlayer pressure-sensitive adhesive layer and the support layer. In particular, when a woven fabric having an opening as in the present invention is used as the polishing layer, the opening of the woven fabric penetrates in the thickness direction, so that the polishing slurry easily reaches the interlayer adhesive layer. Therefore, the polishing layer is easy to peel off, and it is necessary to improve durability as a polishing pad. In that respect, an adhesive tape made of a silicone composition has high water repellency and excellent chemical resistance. Therefore, even if the polishing pad is immersed in the polishing slurry, it has an adhesive force equivalent to that at the time of drying, and the durability as the polishing pad can be dramatically improved, which is preferable.

  Even when a chemically reactive adhesive is used as an interlayer adhesive layer, the adhesive is required to be resistant to polishing slurry, and the adhesive composition is an epoxy, urethane, acrylic reactive, or modified silicone adhesive. An agent can be used. When thermoplastic urethane is used as the support layer, it is more preferable to use a urethane-based adhesive that exhibits excellent adhesion to urethane. Moreover, it is more preferable to use a modified silicone adhesive because it can absorb more vibrations generated during polishing.

  For chemically reactive adhesives, use a gravure coater or knife coater to apply directly to the surface of the support layer, or indirectly transfer the adhesive applied to the process paper to the support layer. be able to.

  When using thermoplastic resin fusion as the interlayer adhesive layer, it is possible to appropriately select a thermoplastic resin such as polyamide, polyolefin, polyurethane, ethylene vinyl alcohol (EVA), or polyester as the thermoplastic resin. it can.

  In the present invention, the form of the thermoplastic resin is preferably a sheet-like thermoadhesive film so that the flatness of the polished surface is not impaired. Commercially available thermal adhesive films include “Elfan NT” (polyamide), “Elfan UH” (polyurethane), “Elfan PH” (polyester), and “Elfan OH” manufactured by Nippon Matai Co., Ltd. "(EVA type)", "Daiamide film" manufactured by Daicel Finechem Co., Ltd., and the like.

  Further, when the fabric is directly bonded and laminated by heating and softening the surface of the support made of the thermoplastic resin, the adhesive interface is reduced as compared with other bonding methods, so that the possibility of the fabric peeling can be reduced. In addition, since the interlayer adhesive layer itself is not necessary, it can contribute to cost reduction and yield improvement in manufacturing the polishing pad.

  Next, a specific aspect of the manufacturing method of the polishing pad of the present invention will be described.

  As shown in FIG. 1, the polishing pad of the present invention is composed of a laminate of a polishing layer, an interlayer adhesive layer, a support layer and a surface plate adhesive layer, and a surface plate adhesive layer is laminated on one surface of the support layer. A polishing pad can be produced by forming a groove on the other surface and then successively laminating the interlayer adhesive layer and the fabric.

  It is preferable to use a thermoplastic urethane resin sheet as the support layer. A laminator is used to laminate a pressure-sensitive adhesive tape for a surface plate, and then the surface of the support layer is cut to form a lattice or radial groove.

  For the lamination of the polishing layer on the grooved support layer, a pressure sensitive adhesive or a chemically reactive adhesive is used. When using a pressure-sensitive adhesive, a double-sided adhesive tape is laminated on the surface layer of the support layer grooved using a laminator, and the adhesive tape covering the top of the groove is cut and removed to produce an interlayer adhesive layer. When using a chemically reactive adhesive, the adhesive applied to the process paper is transferred to the support layer and laminated.

  After forming the interlayer adhesive layer, the polishing layer is laminated to produce the polishing pad of the present invention.

  Next, an example of the wafer flatness evaluation method used in the present invention will be described.

  As the polishing machine, a single-side polishing machine “ADP-800” (registered trademark) manufactured by Fujikoshi Machine Industry Co., Ltd. is used. As a polishing slurry, “GLANZOX2102” (registered trademark) manufactured by Fujimi Incorporated, which is an aqueous dispersion of colloidal silica, is registered. Trademark). The wafer to be polished is polished using a 300 mm single crystal silicon etched wafer manufactured by Shin-Etsu Semiconductor.

  In the present invention, GBIR, which is an index of flatness of the entire wafer, and SFQR, which is an index of flatness of the site size, are measured using a flatness measuring device “Wafercom 300 Spirit” manufactured by Lapmaster SFT Co., Ltd.

  The polishing pad of the present invention is not only used for polishing silicon (Si) wafers, annealed wafers, epi wafers, SOI wafers, embedded wafers, bonded wafers, and reclaimed wafers, but also gallium nitride (GaN) and gallium as semiconductor polishing objects. It can also be used for polishing compound semiconductor wafers such as arsenic (GaAs), silicon carbide (SiC), and sapphire. Further, the present invention is not limited to polishing a semiconductor wafer, but can be used for CMP after forming an oxide film, a metal film, or the like, or for polishing a back grind after forming an element. Furthermore, it can be used for various polishing applications such as polishing of hard disk substrates such as aluminum disks and glass disks, and glass polishing of glass for liquid crystal displays, optical glass and photomasks.

  Hereinafter, the polishing pad of this invention is demonstrated in detail using an Example. The measurement described in the examples was performed by the following method.

A. SEM Observation Platinum was vapor-deposited on the sample and observed at a predetermined magnification using an ultra-high resolution electrolytic emission scanning electron microscope “JSM-5400LV” manufactured by JEOL.

B. Apertures of woven fabric The surface of the polishing pad was observed at a magnification of 100 with the above SEM apparatus, the apertures were specified, the aperture areas were measured at 20 different locations, and the average value of the square roots was defined as the aperture size. As shown in FIG. 4, the mesh means pores formed by being surrounded by warps and wefts of a fabric, and these pores penetrate through the fabric in the thickness direction.

C. Polishing Layer Thickness The cross section of the woven fabric was chamfered by cutting the polishing pad with a razor. Subsequently, the cross section of the pad was observed with an SEM at a magnification of 500 times, and the distance between the warp surface on the fabric surface and the weft surface on the back surface of the fabric at the intersection of the warp and the weft was measured. The measurement was performed at five different locations in the same fabric, and the average value was taken as the thickness of the fabric.

D. Polishing Evaluation As a polishing machine, a single-side polishing machine “ADP-800” (registered trademark) manufactured by Fujikoshi Machine Industry Co., Ltd. was used. As the polishing pad, the polishing pads produced in Examples and Comparative Examples were used, respectively, and “GLANZOX2102” (registered trademark) manufactured by Fujimi Incorporated, which is an aqueous dispersion of colloidal silica, was used as the polishing slurry. A single crystal silicon etched wafer having a diameter of 300 mm was used as an object to be polished, and 6 wafers were used for polishing for a total of 2 hours. The polishing conditions at this time are as follows.

  Moreover, between batches, RO water dressing is performed for 120 seconds at a discharge pressure of 13 MPa with an ultra high pressure micro jet precision cleaning device “AF2800S” manufactured by Asahi Sunac Co., Ltd. to clean and remove polishing debris and slurry remaining on the polishing pad. did.

<Polishing conditions>
・ Surface plate speed: 40rpm
Polishing pressure: 3.0 psi
-Polishing time: 20 minutes / sheet-Number of wafers polished: 6 Evaluation of wafer flatness after polishing Using a flatness measuring device “Wafercom 300 Spirit” manufactured by Lapmaster SFT Co., Ltd., polishing rate, GBIR which is an index of flatness of the entire wafer, and an index of site size flatness SFQR was evaluated. Further, the polishing rate of the sixth wafer was also measured, and the transition of the polishing rate over time was evaluated. At this time, the measurement exclusion area was 3.0 mm, and SFQR was measured at a site size of 33 × 25 mm.

[Example 1]
A thermoplastic urethane resin sheet having an Asker A hardness of 90 and a thickness of 0.5 mm was used as the support layer, and an acrylic pressure-sensitive adhesive tape (film substrate) for surface plate adhesion was laminated on one surface. The other surface of the support layer is cut to form a lattice-shaped groove on the surface of the support layer having a groove pitch of 20 mm, a groove width of 2.0 mm, and a groove depth of 0.3 mm (groove cross-sectional area of 0.6 mm ² ). Formed. After a silicone double-sided adhesive tape (film substrate) was bonded to the surface layer of the support layer with a laminator, the adhesive tape covering the groove was cut using a design knife. The release paper of the adhesive tape was peeled off, and a strong twisted yarn woven fabric that became the polishing layer was bonded to prepare a polishing pad. At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Here, the strongly twisted yarn fabric used as the polishing layer is composed of a fiber bundle in which multifilaments of 17 dtex-12 filaments (triangular cross section) are strongly twisted at 1,700 T / m. The warp density was 157 / inch, the weft density was 176 / inch, the mesh opening was 86 μm, and the fabric thickness was 70 μm (Table 1).

  Using the obtained polishing pad, a silicon etched wafer having a diameter of 300 mm was polished and the flatness of the wafer was evaluated. The polishing rate was 0.27 μm / min. Further, GBIR was 1.30 μm and SFQR was 0.27 μm, and the wafer flatness was excellent. The polishing rate of the sixth wafer was 0.29 μm / min, and no decrease in polishing rate over time was confirmed (Table 1).

[Example 2]
A thermoplastic urethane resin sheet having an Asker A hardness of 90 and a thickness of 0.5 mm was used as the support layer, and an acrylic pressure-sensitive adhesive tape (film substrate) for surface plate adhesion was laminated on one surface. The other surface of the support layer is cut to form 16 radial grooves having a groove pitch of 20 mm, a groove width of 2.0 mm, and a groove depth of 0.3 mm (groove cross-sectional area of 0.6 mm ² ) on the surface layer of the support layer. The book was formed. After a silicone double-sided adhesive tape (film substrate) was bonded to the surface layer of the support layer with a laminator, the adhesive tape covering the groove was cut using a design knife. The release paper of the pressure-sensitive adhesive tape was peeled off, and a monofilament fabric serving as a polishing layer was bonded to prepare a polishing pad. At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Here, the woven fabric used as the polishing layer was a plain woven fabric composed of monofilaments having a fiber diameter of 45 μm, with an opening of 82 μm and a woven fabric thickness of 68 μm (Table 1).

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was 0.25 μm / min. Moreover, GBIR was 1.41 μm and SFQR was 0.29 μm, and the wafer flatness was excellent. The polishing rate of the sixth wafer was 0.26 μm / min, and no decrease in the polishing rate over time was confirmed.

[Example 3]
A polishing pad was produced in the same manner as in Example 1 except that a strongly twisted yarn fabric different from that in Example 1 was used. Strong twisted yarn fabric consists of a fiber bundle in which multifilaments of 17 dtex-12 filaments (triangular cross section) are strongly twisted at 3,000 T / m, with a warp density of 295 / inch, a weft density of 150 / inch, and an opening of 132 μm The fabric thickness was 110 μm (Table 1). At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was 0.29 μm / min. Moreover, GBIR was 1.78 μm and SFQR was 0.27 μm, and the wafer flatness was relatively excellent. The polishing rate of the sixth wafer was 0.30 μm, and no decrease in the polishing rate over time was confirmed.

[Example 4]
A polishing pad in the same manner as in Example 1 except that a lattice-like groove having a groove pitch of 20 mm, a groove width of 3.0 mm, and a groove depth of 0.6 mm (groove cross-sectional area of 1.8 mm ² ) was formed on the surface layer of the support layer. Was made. (Table 1). At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was 0.31 μm / min. Moreover, GBIR was 1.87 μm and SFQR was 0.31 μm, and the wafer flatness was relatively excellent. The polishing rate of the sixth wafer was 0.33 μm / min, and no decrease in the polishing rate over time was confirmed.

[Example 5]
A thermoplastic urethane resin sheet having an Asker A hardness of 90 and a thickness of 0.5 mm was used as the support layer, and an acrylic pressure-sensitive adhesive tape (film substrate) for surface plate adhesion was laminated on one surface. The other surface of the support layer is cut to form a lattice-like groove having a groove pitch of 20 mm, a groove width of 1.0 mm, and a groove depth of 0.2 mm (groove cross-sectional area of 0.2 mm ² ) on the surface of the support layer. Formed. A urethane-based adhesive was applied to the process paper with an adhesive thickness of 30 μm, and was bonded to the surface layer of the support layer, so that the adhesive was transferred only to the surface layer of the support layer so as not to adhere in the groove. Subsequently, a strong twisted yarn fabric was laminated to prepare a polishing pad. Here, as the polishing layer, the same strongly twisted yarn fabric as in Example 1 was used (Table 1). At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was 0.20 μm / min. Further, GBIR was 1.92 μm, SFQR was 0.31 μm, and the wafer flatness was relatively excellent. The polishing rate of the sixth wafer was 0.19 μm / min, and although the polishing rate was slightly lowered, it was almost maintained.

[Example 6]
A polishing pad in the same manner as in Example 1 except that concentric grooves having a groove pitch of 20 mm, a groove width of 2.0 mm, and a groove depth of 0.3 mm (groove cross-sectional area of 0.6 mm ² ) were formed on the surface layer of the support layer. (Table 1). At this time, the polishing surface and the groove communicated with each other via the polishing layer and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was 0.20 μm / min. GBIR was 2.18 μm and SFQR was 0.32 μm. The polishing rate of the sixth wafer was 0.18 μm / min.

[Comparative Example 1]
A polishing pad was produced in the same manner as in Example 1 except that no groove was formed on the surface layer of the support layer (Table 1).

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished and the flatness of the wafer was evaluated. The polishing rate was as small as 0.11 μm / min. GBIR was 2.99 μm, and SFQR was 0.44 μm, which was inferior in flatness. The polishing rate of the sixth wafer was 0.07 μm / min, and the polishing rate decreased with time.

[Comparative Example 2]
A polishing pad was prepared in the same manner as in Example 1 except that another woven fabric was used as the polishing layer. Here, the woven fabric used as the polishing layer is a non-twisted multifilament plain woven fabric. Both the warp is 84 dtex-18 filament (single fiber diameter 17 μm) and the weft is 84 dtex-36 filament (single fiber diameter 15 μm). Consists of straight yarn without shrinkage. The thickness of the woven fabric was 120 μm, and the opening was 30 μm (Table 1). At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished, and the flatness of the wafer was evaluated. The polishing rate was 0.15 μm / min. GBIR was 2.38 μm, and SFQR was 0.38 μm, which was inferior in flatness. The polishing rate of the sixth wafer was 0.10 μm / min, and the polishing rate decreased with time.

[Comparative Example 3]
A polishing pad was produced in the same manner as in Example 1 except that another strong twisted yarn fabric was used as the polishing layer. Here, the strongly twisted yarn fabric used as the polishing layer is a fiber bundle in which 40 dtex-25 filament multifilament is strongly twisted at 1,700 T / m, the warp density is 157 strands / inch, the weft density is 176 strands / inch, The mesh opening was 62 μm, and the fabric thickness was 130 μm (Table 1). At this time, a part of the polished surface and the groove communicated with each other through the mesh openings and the interlayer adhesive layer.

  Using the obtained polishing pad, a φ300 mm silicon etched wafer was polished, and the flatness of the wafer was evaluated. The polishing rate was 0.17 μm / min. GBIR was 2.25 μm and SFQR was 0.36 μm, which was inferior in flatness. The polishing rate of the sixth wafer was 0.14 μm / min, and the polishing rate decreased with time.

  The results are shown in Table 1.

1: Polishing layer 2: Interlayer adhesive layer 3: Support layer 4: Surface plate adhesive layer 5: Groove 6: Fabric thickness 7: Opening

Claims (4)

  A polishing pad formed by laminating a polishing layer and a support layer. The polishing layer is made of a woven fabric having an opening of 50 to 200 μm and a thickness of 100 μm or less, and a groove is formed in the support layer, and the groove is polished. A polishing pad that communicates with a surface.   The polishing pad according to claim 1, wherein the polishing layer is a twisted woven fabric. The polishing pad according to claim 1, wherein the groove has a cross-sectional area of 0.1 to ² mm ² .   The polishing pad according to claim 1, wherein the groove formed in the support layer has a lattice shape or a radial shape.